Evolved to be eaten? Plant traits, herbivory history and biogeochemistry

DÍAZ S

Palmestorn North, Nueva Zelanda

Congreso; 49th Symposium of the International Association for Vegetation Science; 2007

International Association for Vegetation Science

Herbivory by vertebrates is one of the most important forces structuring vegetation and driving ecosystem processes. There are universal plant-trait syndromes, associated to more general plant resource-use strategies, that favour or deter herbivory and thus regulate trophic transfer and nutrient cycling. On the other hand, herbivory alters plant traits and community texture at the ecological and evolutionary scales. Although these are well-know facts, the effects of ecological sorting and natural selection exerted by vertebrate herbivores on ecosystem processes have been rarely considered empirically and at a large scale. Two lines of evidence are presented, suggesting that  herbivory pressure over evolutionary time models plant trait responses to grazing and thus ecosystem functioning. The first is a global scale meta-analysis of plant traits affected  by grazing. This shows that globally-consistent response patterns were modified by particular combinations of precipitation and herbivory history.The second combines the comparative study of leaf traits and biogeochemical modeling, and suggests that over evolutionary time generalist vertebrate herbivores select for more acquisitive plant traits, thus shifting nutrient cycling towards more open carbon and nitrogen cycles with faster turnover rate. These findings point to key plant traits that need to be included in the next generation of dynamic global vegetation models, and suggest that plant functional type classifications and response rules need to be specific to regions with different climate and history of herbivory.